1. Technical Field
The present invention relates to a hydraulic engine mount in which an interior is divided by a nozzle plate into an upper liquid chamber and a lower liquid chamber, and an encapsulated hydraulic liquid flows between the upper liquid chamber and the lower liquid chamber through a flow path formed in the nozzle plate, and more particularly, to an engine mount capable of tuning and customizing damping characteristics by changing a length of the flow path even after the engine mount is mounted.
2. Description of the Related Art
An engine for a vehicle is installed in an engine room of a vehicle body through an engine mount in order to insulate or attenuate vibration of the engine, and a rubber mount for insulating and attenuating vibration using elastic force of rubber and a hydraulic engine mount in which a predetermined amount of a hydraulic liquid is encapsulated are widely used for a passenger vehicle.
Among the mounts, the hydraulic engine mount has a structure in which a predetermined amount of hydraulic liquid is encapsulated therein and vibration is attenuated by a flow of the hydraulic liquid, and has an effect of simultaneously attenuating vibration in a high frequency region and a low frequency region, such that a range of application of the hydraulic engine mount is increased.
As illustrated in FIG. 1, the hydraulic engine mount has a structure in which an insulator 4 made of an elastic material is coupled at an upper side inside a case, a diaphragm 5 is coupled at a lower end, a nozzle plate 6 is mounted between the insulator 4 and the diaphragm 5, and an internal space is divided into an upper liquid chamber and a lower liquid chamber.
The nozzle plate 6 is configured by coupling a nozzle lower portion 9 and a nozzle upper portion 7. The nozzle lower portion 9 has a doughnut shape having a hole formed at a center thereof, and has a structure in which an annular flow path groove, which constitutes a lower portion of a flow path, is formed along an outer circumference of the central hole. A lower flow path hole is formed in a bottom surface at one end of the flow path groove so as to communicate with the lower liquid chamber.
A membrane 8 (which vibrates when the hydraulic liquid flows) and the nozzle upper portion 7, which is formed in a ring shape so as to prevent the membrane 8 from being separated, are sequentially at a center above the nozzle lower portion 9. An upper flow path hole is formed in the nozzle upper portion 7 so as to be connected to the other end of the flow path groove and to communicate with the upper liquid chamber.
That is, the upper side of the flow path groove is closed by the nozzle upper portion 7, and as a result, a ‘flow path’ through which the hydraulic liquid may flow is formed in the nozzle plate 6. Therefore, one side of the flow path communicates with the upper liquid chamber through the upper flow path hole, and the other side of the flow path communicates with the lower liquid chamber through the lower flow path hole.
Therefore, the hydraulic liquid flows through the flow path as an internal volume of the upper liquid chamber is increased or decreased when a bolt 1 connected with an engine (not illustrated) is mounted and the insulator 4 coupled to a core 3 (which moves in accordance with vibration and movement of a load transmitted from an engine) is elastically deformed. For reference, the bolt 1 is sometimes manufactured integrally with the core 3, but as illustrated, a bolt hole 2 is formed in the core 3, threads are formed on a head of the bolt 1, and the bolt 1 and the core 3 are fastened in a threaded connection manner.
Meanwhile, at the time of developing an engine mount, the engine mount is designed in consideration of ride quality and handling (ride & handling) and NVH (noise, vibration, harshness) performance, and a damping frequency is frequently required to be changed during developing, evaluating, and producing steps.
That is, an engine mount needs to be constantly tuned from a step of initially developing a vehicle until the vehicles are mass-produced. In particular, significant amounts of time and costs are required, and considerable losses of time and costs occur when a mold for mass-production is required to be changed after the mold for mass-production is initially made.
A customer, who purchases the vehicle, has various expectations with respect to traveling performance of the vehicle. That is, the customer may have preferences concerning traveling performance of the vehicle or NVH performance. However, there is a problem in that once the engine mount is mounted in a mass-produced vehicle, personal tuning is nearly impossible.